How does my heat pump work?

It may be puzzling to notice that no matter the season your central outdoor unit runs summer and winter. As incredible as it sounds one refrigeration system can produce cooling in the summer and heat your home in the winter.

Your system takes heat out of your home in the summer and releases it outdoors. The hot/humid air in your home is blown across the indoor coil, absorbed into the refrigerant, and sent outdoor to your outdoor unit. It is then released by the outdoor coil with the air generated by the condenser fan.In the winter the cycle is reversed. When you transfer to heating cycle in the fall of the year you select heat on your thermostat and the reversing valve is initiated. The refrigerant flow now uses the outdoor coil to absorb the heat (BTUs) from the surrounding air to heat your home. It does not sound possible but heat (BTUs) can be absorbed with temperatures below 32 degF. There is a balance point when the heat required for your home exceeds what the heat pump alone can provide. As the temperature lowers the amount of collectable heat is reduced. At that balance point the system will energize a supplemental electric heater to assist the unit to provide enough heat to satisfy the setting on your thermostat. Also, during time when the outdoor temperature is near the balance point or below your system will run constantly. Do not be concerned this is normal operation; the air coming out of your registers will feel cool compared to your body temperature. For example at 40 degF outdoor temperature you heat pump will provide an air temperature of 72-75 degF enough to maintain a thermostat set in that range. Since our body temperature is 98.6 degF setting close to or walking by a register will feel cool.

If you notice that the electric heat/emergency heat light on your thermostat stays on constantly or more than normal during these lower temperatures contact Tennessee Mechanical to have a technician check the operation. This is just a pre-cautionary step to make sure the system is operating properly.

One other thing you may notice is that during high humidity days in the winter months (snow/rainy days) ice will collect on your outdoor unit coils. Again do not be overly concerned because this is normal operation. The system will automatically de-ice the coil when it begins to restrict proper operation. If you notice that the coil is covered with ice and not going into the defrost mode, start checking your unit periodically. The defrost/de-ice cycle can be identified by the swooshing sound and seeing steam rising from the unit. If you have any concerns that the unit is not defrosting properly contact Tennessee Mechanical immediately for system analysis. If this condition goes undetected it will increase your electric utility bill dramatically. When the outdoor coil is restricted with ice it cannot absorb heat which means that you’re heating your home with the electric heat strips. If you are not diligent in periodically checking your system this can be a very unpleasant surprise when you receive your monthly utility notice.

Please feel free to contact TMC if you suspect that your system is not operating properly to maintain your home comfort and peace of mind.